In many gear trains, the position of each gear in the gear train must be set to ensure proper mating of the gear teeth. This is of particular importance in differential assemblies of power driven vehicles, which play a key role in transferring power from the vehicle engine to the wheels of the vehicle by means of a pinion gear and a ring gear. Both the pinion and ring gears are typically enclosed within a differential housing with several other components of the differential assembly. The ring gear has an axis of rotation which is perpendicular to that of the pinion gear and is operatively connected to a pair of shafts mounted within carrier bearings that are secured on opposite sides of the differential housing within respective semi-circular bearing seats. The pinion gear is mounted upon the end of a drive shaft, and its position relative to the ring gear is typically adjusted by the use of shims or other suitable adjustment devices mounted between a bearing which supports the shaft of the pinion gear and a head thereof.
Oftentimes some of the parts within the differential housing need to be replaced because of wear or breakage. This process usually involves removing the ring gear from the differential housing so that the position of the pinion gear must be measured and adjusted before the ring gear is replaced to ensure proper mating of the gears. Manufacturers customarily provide a specification for setting the proper mating points of the pinion and ring gears. Many times this is specified in the form of a “pinion depth,” which is the distance from an end face of the pinion gear to an axis of rotation of the ring gear. Therefore, an accurate measurement tool is needed to determine the depth of the pinion gear to ensure that the gears are mounted according to specification.
Measurement tools known in the art for determining the depth of a pinion gear in a differential assembly involve the use of a shaft or crossbar member that is secured in the bearing seats provided on the opposite sides of the differential housing so as to extend along the rotational axis of the ring gear. A measuring gage is mounted to slide along the shaft until it is positioned over an end face of the pinion gear. In this position, the measurement gage is adjusted until it contacts the end face of the pinion gear. The pinion depth is determined from the measurement obtained by the measurement gage.
Many of the measurement tools known in the art require additional parts that must be interchanged when different sizes of differential assemblies are encountered. These additional parts not only increase the cost of such tools, but also make the measurement process more cumbersome and time consuming. Tools that can be adapted to variations in differential assembly sizes still involve numerous parts that must be properly adjusted before taking any measurement. Such tools are difficult to use and may lead to inaccurate measurements.
Accordingly, a measurement tool is needed for determining the depth of a pinion gear in a differential assembly that involves a minimum number of parts, is relatively inexpensive to make, and can be easily operated to obtain accurate measurement results.